/*****************************************************************************/
/*                                                                           */
/*                                 symtab.c                                  */
/*                                                                           */
/*              Symbol table management for the cc65 C compiler              */
/*                                                                           */
/*                                                                           */
/*                                                                           */
/* (C) 2000-2013, Ullrich von Bassewitz                                      */
/*                Roemerstrasse 52                                           */
/*                D-70794 Filderstadt                                        */
/* EMail:         uz@cc65.org                                                */
/*                                                                           */
/*                                                                           */
/* This software is provided 'as-is', without any expressed or implied       */
/* warranty.  In no event will the authors be held liable for any damages    */
/* arising from the use of this software.                                    */
/*                                                                           */
/* Permission is granted to anyone to use this software for any purpose,     */
/* including commercial applications, and to alter it and redistribute it    */
/* freely, subject to the following restrictions:                            */
/*                                                                           */
/* 1. The origin of this software must not be misrepresented; you must not   */
/*    claim that you wrote the original software. If you use this software   */
/*    in a product, an acknowledgment in the product documentation would be  */
/*    appreciated but is not required.                                       */
/* 2. Altered source versions must be plainly marked as such, and must not   */
/*    be misrepresented as being the original software.                      */
/* 3. This notice may not be removed or altered from any source              */
/*    distribution.                                                          */
/*                                                                           */
/*****************************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>

/* common */
#include "check.h"
#include "debugflag.h"
#include "hashfunc.h"
#include "xmalloc.h"

/* cc65 */
#include "asmcode.h"
#include "asmlabel.h"
#include "codegen.h"
#include "datatype.h"
#include "declare.h"
#include "error.h"
#include "funcdesc.h"
#include "global.h"
#include "stackptr.h"
#include "symentry.h"
#include "typecmp.h"
#include "symtab.h"
#include "function.h"
#include "input.h"

/*****************************************************************************/
/*                                   Data                                    */
/*****************************************************************************/

/* An empty symbol table */
SymTable EmptySymTab = {
    0,  /* PrevTab */
    0,  /* SymHead */
    0,  /* SymTail */
    0,  /* SymCount */
    1,  /* Size */
    {0} /* Tab[1] */
};

/* Symbol table sizes */
#define SYMTAB_SIZE_GLOBAL 211U
#define SYMTAB_SIZE_FUNCTION 29U
#define SYMTAB_SIZE_BLOCK 13U
#define SYMTAB_SIZE_STRUCT 19U
#define SYMTAB_SIZE_LABEL 7U

/* The current and root symbol tables */
static unsigned LexicalLevel = 0; /* For safety checks */
static SymTable *SymTab0 = 0;
static SymTable *SymTab = 0;
static SymTable *TagTab0 = 0;
static SymTable *TagTab = 0;
static SymTable *LabelTab = 0;
static SymTable *SPAdjustTab = 0;

/*****************************************************************************/
/*                              struct SymTable                              */
/*****************************************************************************/

static SymTable *NewSymTable(unsigned Size)
/* Create and return a symbol table for the given lexical level */
{
  unsigned I;

  /* Allocate memory for the table */
  SymTable *S = xmalloc(sizeof(SymTable) + (Size - 1) * sizeof(SymEntry *));

  /* Initialize the symbol table structure */
  S->PrevTab = 0;
  S->SymHead = 0;
  S->SymTail = 0;
  S->SymCount = 0;
  S->Size = Size;
  for (I = 0; I < Size; ++I) {
    S->Tab[I] = 0;
  }

  /* Return the symbol table */
  return S;
}

static void FreeSymTable(SymTable *S)
/* Free the given symbo table including all symbols */
{
  /* Free all symbols */
  SymEntry *Sym = S->SymHead;
  while (Sym) {
    SymEntry *NextSym = Sym->NextSym;
    FreeSymEntry(Sym);
    Sym = NextSym;
  }

  /* Free the table itself */
  xfree(S);
}

/*****************************************************************************/
/*                         Check symbols in a table                          */
/*****************************************************************************/

static void CheckSymTable(SymTable *Tab)
/* Check a symbol table for open references, unused symbols ... */
{
  SymEntry *Entry = Tab->SymHead;
  while (Entry) {

    /* Get the storage flags for tne entry */
    unsigned Flags = Entry->Flags;

    /* Ignore typedef entries */
    if (!SymIsTypeDef(Entry)) {

      /* Check if the symbol is one with storage, and it if it was
      ** defined but not used.
      */
      if (((Flags & SC_AUTO) || (Flags & SC_STATIC)) && (Flags & SC_EXTERN) == 0) {
        if (SymIsDef(Entry) && !SymIsRef(Entry) && !SymHasAttr(Entry, atUnused)) {
          if (Flags & SC_PARAM) {
            if (IS_Get(&WarnUnusedParam)) {
              Warning("Parameter '%s' is never used", Entry->Name);
            }
          } else {
            if (IS_Get(&WarnUnusedVar)) {
              Warning("'%s' is defined but never used", Entry->Name);
            }
          }
        }
      }

      /* If the entry is a label, check if it was defined in the function */
      if (Flags & SC_LABEL) {
        if (!SymIsDef(Entry)) {
          /* Undefined label */
          Error("Undefined label: '%s'", Entry->Name);
        } else if (!SymIsRef(Entry)) {
          /* Defined but not used */
          if (IS_Get(&WarnUnusedLabel)) {
            Warning("'%s' is defined but never used", Entry->Name);
          }
        }
      }
    }

    /* Next entry */
    Entry = Entry->NextSym;
  }
}

/*****************************************************************************/
/*                        Handling of lexical levels                         */
/*****************************************************************************/

unsigned GetLexicalLevel(void)
/* Return the current lexical level */
{
  return LexicalLevel;
}

void EnterGlobalLevel(void)
/* Enter the program global lexical level */
{
  /* Safety */
  PRECONDITION(++LexicalLevel == LEX_LEVEL_GLOBAL);

  /* Create and assign the symbol table */
  SymTab0 = SymTab = NewSymTable(SYMTAB_SIZE_GLOBAL);

  /* Create and assign the tag table */
  TagTab0 = TagTab = NewSymTable(SYMTAB_SIZE_GLOBAL);

  /* Create and assign the table of SP adjustment symbols */
  SPAdjustTab = NewSymTable(SYMTAB_SIZE_GLOBAL);
}

void LeaveGlobalLevel(void)
/* Leave the program global lexical level */
{
  /* Safety */
  PRECONDITION(LexicalLevel-- == LEX_LEVEL_GLOBAL);

  /* Check the tables */
  CheckSymTable(SymTab0);

  /* Dump the tables if requested */
  if (Debug) {
    PrintSymTable(SymTab0, stdout, "Global symbol table");
    PrintSymTable(TagTab0, stdout, "Global tag table");
  }

  /* Don't delete the symbol and struct tables! */
  SymTab = 0;
  TagTab = 0;
}

void EnterFunctionLevel(void)
/* Enter function lexical level */
{
  SymTable *S;

  /* New lexical level */
  ++LexicalLevel;

  /* Get a new symbol table and make it current */
  S = NewSymTable(SYMTAB_SIZE_FUNCTION);
  S->PrevTab = SymTab;
  SymTab = S;

  /* Get a new tag table and make it current */
  S = NewSymTable(SYMTAB_SIZE_FUNCTION);
  S->PrevTab = TagTab;
  TagTab = S;

  /* Create and assign a new label table */
  S = NewSymTable(SYMTAB_SIZE_LABEL);
  S->PrevTab = LabelTab;
  LabelTab = S;
}

void RememberFunctionLevel(struct FuncDesc *F)
/* Remember the symbol tables for the level and leave the level without checks */
{
  /* Leave the lexical level */
  --LexicalLevel;

  /* Remember the tables */
  F->SymTab = SymTab;
  F->TagTab = TagTab;

  /* Don't delete the tables */
  SymTab = SymTab->PrevTab;
  TagTab = TagTab->PrevTab;
  LabelTab = LabelTab->PrevTab;
}

void ReenterFunctionLevel(struct FuncDesc *F)
/* Reenter the function lexical level using the existing tables from F */
{
  /* New lexical level */
  ++LexicalLevel;

  /* Make the tables current again */
  F->SymTab->PrevTab = SymTab;
  SymTab = F->SymTab;

  F->TagTab->PrevTab = TagTab;
  TagTab = F->TagTab;

  /* Create and assign a new label table */
  LabelTab = NewSymTable(SYMTAB_SIZE_LABEL);
}

void LeaveFunctionLevel(void)
/* Leave function lexical level */
{
  /* Leave the lexical level */
  --LexicalLevel;

  /* Check the tables */
  CheckSymTable(SymTab);
  CheckSymTable(LabelTab);

  /* Drop the label table if it is empty */
  if (LabelTab->SymCount == 0) {
    FreeSymTable(LabelTab);
  }

  /* Don't delete the tables */
  SymTab = SymTab->PrevTab;
  TagTab = TagTab->PrevTab;
  LabelTab = 0;
}

void EnterBlockLevel(void)
/* Enter a nested block in a function */
{
  SymTable *S;

  /* New lexical level */
  ++LexicalLevel;

  /* Get a new symbol table and make it current */
  S = NewSymTable(SYMTAB_SIZE_BLOCK);
  S->PrevTab = SymTab;
  SymTab = S;

  /* Get a new tag table and make it current */
  S = NewSymTable(SYMTAB_SIZE_BLOCK);
  S->PrevTab = TagTab;
  TagTab = S;
}

void LeaveBlockLevel(void)
/* Leave a nested block in a function */
{
  /* Leave the lexical level */
  --LexicalLevel;

  /* Check the tables */
  CheckSymTable(SymTab);

  /* Don't delete the tables */
  SymTab = SymTab->PrevTab;
  TagTab = TagTab->PrevTab;
}

void EnterStructLevel(void)
/* Enter a nested block for a struct definition */
{
  SymTable *S;

  /* Get a new symbol table and make it current. Note: Structs and enums
  ** nested in struct scope are NOT local to the struct but visible in the
  ** outside scope. So we will NOT create a new struct or enum table.
  */
  S = NewSymTable(SYMTAB_SIZE_BLOCK);
  S->PrevTab = SymTab;
  SymTab = S;
}

void LeaveStructLevel(void)
/* Leave a nested block for a struct definition */
{
  /* Don't delete the table */
  SymTab = SymTab->PrevTab;
}

/*****************************************************************************/
/*                              Find functions                               */
/*****************************************************************************/

static SymEntry *FindSymInTable(const SymTable *T, const char *Name, unsigned Hash)
/* Search for an entry in one table */
{
  /* Get the start of the hash chain */
  SymEntry *E = T->Tab[Hash % T->Size];
  while (E) {
    /* Compare the name */
    if (strcmp(E->Name, Name) == 0) {
      /* Found */
      return E;
    }
    /* Not found, next entry in hash chain */
    E = E->NextHash;
  }

  /* Not found */
  return 0;
}

static SymEntry *FindSymInTree(const SymTable *Tab, const char *Name)
/* Find the symbol with the given name in the table tree that starts with T */
{
  /* Get the hash over the name */
  unsigned Hash = HashStr(Name);

  /* Check all symbol tables for the symbol */
  while (Tab) {
    /* Try to find the symbol in this table */
    SymEntry *E = FindSymInTable(Tab, Name, Hash);

    /* Bail out if we found it */
    if (E != 0) {
      return E;
    }

    /* Repeat the search in the next higher lexical level */
    Tab = Tab->PrevTab;
  }

  /* Not found */
  return 0;
}

SymEntry *FindSym(const char *Name)
/* Find the symbol with the given name */
{
  return FindSymInTree(SymTab, Name);
}

SymEntry *FindGlobalSym(const char *Name)
/* Find the symbol with the given name in the global symbol table only */
{
  return FindSymInTable(SymTab0, Name, HashStr(Name));
}

SymEntry *FindLocalSym(const char *Name)
/* Find the symbol with the given name in the current symbol table only */
{
  return FindSymInTable(SymTab, Name, HashStr(Name));
}

SymEntry *FindTagSym(const char *Name)
/* Find the symbol with the given name in the tag table */
{
  return FindSymInTree(TagTab, Name);
}

SymEntry *FindStructField(const Type *T, const char *Name)
/* Find a struct field in the fields list */
{
  SymEntry *Field = 0;

  /* The given type may actually be a pointer to struct */
  if (IsTypePtr(T)) {
    ++T;
  }

  /* Non-structs do not have any struct fields... */
  if (IsClassStruct(T)) {

    /* Get a pointer to the struct/union type */
    const SymEntry *Struct = GetSymEntry(T);
    CHECK(Struct != 0);

    /* Now search in the struct symbol table. Beware: The table may not
    ** exist.
    */
    if (Struct->V.S.SymTab) {
      Field = FindSymInTable(Struct->V.S.SymTab, Name, HashStr(Name));
    }
  }

  return Field;
}

/*****************************************************************************/
/*                       Add stuff to the symbol table                       */
/*****************************************************************************/

static void AddSymEntry(SymTable *T, SymEntry *S)
/* Add a symbol to a symbol table */
{
  /* Get the hash value for the name */
  unsigned Hash = HashStr(S->Name) % T->Size;

  /* Insert the symbol into the list of all symbols in this level */
  if (T->SymTail) {
    T->SymTail->NextSym = S;
  }
  S->PrevSym = T->SymTail;
  T->SymTail = S;
  if (T->SymHead == 0) {
    /* First symbol */
    T->SymHead = S;
  }
  ++T->SymCount;

  /* Insert the symbol into the hash chain */
  S->NextHash = T->Tab[Hash];
  T->Tab[Hash] = S;

  /* Tell the symbol in which table it is */
  S->Owner = T;
}

SymEntry *AddStructSym(const char *Name, unsigned Type, unsigned Size, SymTable *Tab)
/* Add a struct/union entry and return it */
{
  SymEntry *Entry;

  /* Type must be struct or union */
  PRECONDITION(Type == SC_STRUCT || Type == SC_UNION);

  /* Do we have an entry with this name already? */
  Entry = FindSymInTable(TagTab, Name, HashStr(Name));
  if (Entry) {

    /* We do have an entry. This may be a forward, so check it. */
    if ((Entry->Flags & SC_TYPEMASK) != Type) {
      /* Existing symbol is not a struct */
      Error("Symbol '%s' is already different kind", Name);
    } else if (Size > 0 && Entry->V.S.Size > 0) {
      /* Both structs are definitions. */
      Error("Multiple definition for '%s'", Name);
    } else {
      /* Define the struct size if it is given */
      if (Size > 0) {
        Entry->V.S.SymTab = Tab;
        Entry->V.S.Size = Size;
      }
    }

  } else {

    /* Create a new entry */
    Entry = NewSymEntry(Name, Type);

    /* Set the struct data */
    Entry->V.S.SymTab = Tab;
    Entry->V.S.Size = Size;

    /* Add it to the current table */
    AddSymEntry(TagTab, Entry);
  }

  /* Return the entry */
  return Entry;
}

SymEntry *AddBitField(const char *Name, unsigned Offs, unsigned BitOffs, unsigned Width)
/* Add a bit field to the local symbol table and return the symbol entry */
{
  /* Do we have an entry with this name already? */
  SymEntry *Entry = FindSymInTable(SymTab, Name, HashStr(Name));
  if (Entry) {

    /* We have a symbol with this name already */
    Error("Multiple definition for '%s'", Name);

  } else {

    /* Create a new entry */
    Entry = NewSymEntry(Name, SC_BITFIELD);

    /* Set the symbol attributes. Bit-fields are always of type unsigned */
    Entry->Type = type_uint;
    Entry->V.B.Offs = Offs;
    Entry->V.B.BitOffs = BitOffs;
    Entry->V.B.BitWidth = Width;

    /* Add the entry to the symbol table */
    AddSymEntry(SymTab, Entry);
  }

  /* Return the entry */
  return Entry;
}

SymEntry *AddConstSym(const char *Name, const Type *T, unsigned Flags, long Val)
/* Add an constant symbol to the symbol table and return it */
{
  /* Enums must be inserted in the global symbol table */
  SymTable *Tab = ((Flags & SC_ENUM) == SC_ENUM) ? SymTab0 : SymTab;

  /* Do we have an entry with this name already? */
  SymEntry *Entry = FindSymInTable(Tab, Name, HashStr(Name));
  if (Entry) {
    if ((Entry->Flags & SC_CONST) != SC_CONST) {
      Error("Symbol '%s' is already different kind", Name);
    } else {
      Error("Multiple definition for '%s'", Name);
    }
    return Entry;
  }

  /* Create a new entry */
  Entry = NewSymEntry(Name, Flags);

  /* Enum values are ints */
  Entry->Type = TypeDup(T);

  /* Set the enum data */
  Entry->V.ConstVal = Val;

  /* Add the entry to the symbol table */
  AddSymEntry(Tab, Entry);

  /* Return the entry */
  return Entry;
}

DefOrRef *AddDefOrRef(SymEntry *E, unsigned Flags)
/* Add definition or reference to the SymEntry and preserve its attributes */
{
  DefOrRef *DOR;

  DOR = xmalloc(sizeof(DefOrRef));
  CollAppend(E->V.L.DefsOrRefs, DOR);
  DOR->Line = GetCurrentLine();
  DOR->LocalsBlockId = (long)CollLast(&CurrentFunc->LocalsBlockStack);
  DOR->Flags = Flags;
  DOR->StackPtr = StackPtr;
  DOR->Depth = CollCount(&CurrentFunc->LocalsBlockStack);
  DOR->LateSP_Label = GetLocalLabel();

  return DOR;
}

unsigned short FindSPAdjustment(const char *Name)
/* Search for an entry in the table of SP adjustments */
{
  SymEntry *Entry = FindSymInTable(SPAdjustTab, Name, HashStr(Name));

  if (!Entry) {
    Internal("No SP adjustment label entry found");
  }

  return Entry->V.SPAdjustment;
}

SymEntry *AddLabelSym(const char *Name, unsigned Flags)
/* Add a goto label to the label table */
{
  unsigned i;
  DefOrRef *DOR, *NewDOR;
  /* We juggle it so much that a shortcut will help with clarity */
  Collection *AIC = &CurrentFunc->LocalsBlockStack;

  /* Do we have an entry with this name already? */
  SymEntry *Entry = FindSymInTable(LabelTab, Name, HashStr(Name));
  if (Entry) {

    if (SymIsDef(Entry) && (Flags & SC_DEF) != 0) {
      /* Trying to define the label more than once */
      Error("Label '%s' is defined more than once", Name);
    }

    NewDOR = AddDefOrRef(Entry, Flags);

    /* Walk through all occurrences of the label so far and evaluate
    ** their relationship with the one passed to the function.
    */
    for (i = 0; i < CollCount(Entry->V.L.DefsOrRefs); i++) {
      DOR = CollAt(Entry->V.L.DefsOrRefs, i);

      if ((DOR->Flags & SC_DEF) && (Flags & SC_REF) && (Flags & (SC_GOTO | SC_GOTO_IND))) {
        /* We're processing a goto and here is its destination label.
        ** This means the difference between SP values is already known,
        ** so we simply emit the SP adjustment code.
        */
        if (StackPtr != DOR->StackPtr) {
          g_space(StackPtr - DOR->StackPtr);
        }

        /* Are we jumping into a block with initalization of an object that
        ** has automatic storage duration? Let's emit a warning.
        */
        if ((long)CollLast(AIC) != DOR->LocalsBlockId &&
            (CollCount(AIC) < DOR->Depth || (long)CollAt(AIC, DOR->Depth - 1) != DOR->LocalsBlockId)) {
          Warning("Goto at line %d to label %s jumps into a block with "
                  "initialization of an object that has automatic storage duration",
                  GetCurrentLine(), Name);
        }
      }

      if ((DOR->Flags & SC_REF) && (DOR->Flags & (SC_GOTO | SC_GOTO_IND)) && (Flags & SC_DEF)) {
        /* We're processing a label, let's update all gotos encountered
        ** so far
        */
        if (DOR->Flags & SC_GOTO) {
          SymEntry *E;
          g_userodata();
          g_defdatalabel(DOR->LateSP_Label);
          g_defdata(CF_CONST | CF_INT, StackPtr - DOR->StackPtr, 0);

          /* Optimizer will need the information about the value of SP adjustment
          ** later, so let's preserve it.
          */
          E = NewSymEntry(LocalLabelName(DOR->LateSP_Label), SC_SPADJUSTMENT);
          E->V.SPAdjustment = StackPtr - DOR->StackPtr;
          AddSymEntry(SPAdjustTab, E);
        }

        /* Are we jumping into a block with initalization of an object that
        ** has automatic storage duration? Let's emit a warning.
        */
        if ((long)CollLast(AIC) != DOR->LocalsBlockId &&
            (CollCount(AIC) >= DOR->Depth || (long)CollLast(AIC) >= (long)DOR->Line))
          Warning("Goto at line %d to label %s jumps into a block with "
                  "initialization of an object that has automatic storage duration",
                  DOR->Line, Name);
      }
    }

    Entry->Flags |= Flags;

  } else {

    /* Create a new entry */
    Entry = NewSymEntry(Name, SC_LABEL | Flags);

    /* Set a new label number */
    Entry->V.L.Label = GetLocalLabel();
    Entry->V.L.IndJumpFrom = NULL;

    /* Create Collection for label definition and references */
    Entry->V.L.DefsOrRefs = NewCollection();
    NewDOR = AddDefOrRef(Entry, Flags);

    /* Generate the assembler name of the label */
    Entry->AsmName = xstrdup(LocalLabelName(Entry->V.L.Label));

    /* Add the entry to the label table */
    AddSymEntry(LabelTab, Entry);
  }

  /* We are processing a goto, but the label has not yet been defined */
  if (!SymIsDef(Entry) && (Flags & SC_REF) && (Flags & SC_GOTO)) {
    g_lateadjustSP(NewDOR->LateSP_Label);
  }

  /* Return the entry */
  return Entry;
}

SymEntry *AddLocalSym(const char *Name, const Type *T, unsigned Flags, int Offs)
/* Add a local symbol and return the symbol entry */
{
  /* Do we have an entry with this name already? */
  SymEntry *Entry = FindSymInTable(SymTab, Name, HashStr(Name));
  if (Entry) {

    /* We have a symbol with this name already */
    Error("Multiple definition for '%s'", Name);

  } else {

    /* Create a new entry */
    Entry = NewSymEntry(Name, Flags);

    /* Set the symbol attributes */
    Entry->Type = TypeDup(T);
    if ((Flags & SC_AUTO) == SC_AUTO) {
      Entry->V.Offs = Offs;
    } else if ((Flags & SC_REGISTER) == SC_REGISTER) {
      Entry->V.R.RegOffs = Offs;
      Entry->V.R.SaveOffs = StackPtr;
    } else if ((Flags & SC_EXTERN) == SC_EXTERN) {
      Entry->V.L.Label = Offs;
      SymSetAsmName(Entry);
    } else if ((Flags & SC_STATIC) == SC_STATIC) {
      /* Generate the assembler name from the label number */
      Entry->V.L.Label = Offs;
      Entry->AsmName = xstrdup(LocalLabelName(Entry->V.L.Label));
    } else if ((Flags & SC_STRUCTFIELD) == SC_STRUCTFIELD) {
      Entry->V.Offs = Offs;
    } else {
      Internal("Invalid flags in AddLocalSym: %04X", Flags);
    }

    /* Add the entry to the symbol table */
    AddSymEntry(SymTab, Entry);
  }

  /* Return the entry */
  return Entry;
}

SymEntry *AddGlobalSym(const char *Name, const Type *T, unsigned Flags)
/* Add an external or global symbol to the symbol table and return the entry */
{
  /* There is some special handling for functions, so check if it is one */
  int IsFunc = IsTypeFunc(T);

  /* Functions must be inserted in the global symbol table */
  SymTable *Tab = IsFunc ? SymTab0 : SymTab;

  /* Do we have an entry with this name already? */
  SymEntry *Entry = FindSymInTable(Tab, Name, HashStr(Name));
  if (Entry) {
    Type *EType;

    /* If the existing symbol is an enumerated constant,
    ** then avoid a compiler crash.  See GitHub issue #728.
    */
    if (Entry->Flags & SC_ENUM) {
      Fatal("Can't redeclare enum constant '%s' as global variable", Name);
    }

    /* We have a symbol with this name already */
    if (Entry->Flags & SC_TYPE) {
      Error("Multiple definition for '%s'", Name);
      return Entry;
    }

    /* Get the type string of the existing symbol */
    EType = Entry->Type;

    /* If we are handling arrays, the old entry or the new entry may be an
    ** incomplete declaration. Accept this, and if the exsting entry is
    ** incomplete, complete it.
    */
    if (IsTypeArray(T) && IsTypeArray(EType)) {

      /* Get the array sizes */
      long Size = GetElementCount(T);
      long ESize = GetElementCount(EType);

      if ((Size != UNSPECIFIED && ESize != UNSPECIFIED && Size != ESize) || TypeCmp(T + 1, EType + 1) < TC_EQUAL) {
        /* Types not identical: Conflicting types */
        Error("Conflicting types for '%s'", Name);
        return Entry;
      } else {
        /* Check if we have a size in the existing definition */
        if (ESize == UNSPECIFIED) {
          /* Existing, size not given, use size from new def */
          SetElementCount(EType, Size);
        }
      }

    } else {
      /* New type must be identical */
      if (TypeCmp(EType, T) < TC_EQUAL) {
        Error("Conflicting types for '%s'", Name);
        return Entry;
      }

      /* In case of a function, use the new type descriptor, since it
      ** contains pointers to the new symbol tables that are needed if
      ** an actual function definition follows. Be sure not to use the
      ** new descriptor if it contains a function declaration with an
      ** empty parameter list.
      */
      if (IsFunc) {
        /* Get the function descriptor from the new type */
        FuncDesc *F = GetFuncDesc(T);
        /* Use this new function descriptor if it doesn't contain
        ** an empty parameter list.
        */
        if ((F->Flags & FD_EMPTY) == 0) {
          Entry->V.F.Func = F;
          SetFuncDesc(EType, F);
        }
      }
    }

    /* If a static declaration follows a non-static declaration, then
    ** warn about the conflict.  (It will compile a public declaration.)
    */
    if ((Flags & SC_EXTERN) == 0 && (Entry->Flags & SC_EXTERN) != 0) {
      Warning("static declaration follows non-static declaration of '%s'.", Name);
    }

    /* An extern declaration must not change the current linkage. */
    if (IsFunc || (Flags & (SC_EXTERN | SC_STORAGE)) == SC_EXTERN) {
      Flags &= ~SC_EXTERN;
    }

    /* If a public declaration follows a static declaration, then
    ** warn about the conflict.  (It will compile a public declaration.)
    */
    if ((Flags & SC_EXTERN) != 0 && (Entry->Flags & SC_EXTERN) == 0) {
      Warning("public declaration follows static declaration of '%s'.", Name);
    }

    /* Add the new flags */
    Entry->Flags |= Flags;

  } else {

    /* Create a new entry */
    Entry = NewSymEntry(Name, Flags);

    /* Set the symbol attributes */
    Entry->Type = TypeDup(T);

    /* If this is a function, set the function descriptor and clear
    ** additional fields.
    */
    if (IsFunc) {
      Entry->V.F.Func = GetFuncDesc(Entry->Type);
      Entry->V.F.Seg = 0;
    }

    /* Add the assembler name of the symbol */
    SymSetAsmName(Entry);

    /* Add the entry to the symbol table */
    AddSymEntry(Tab, Entry);
  }

  /* Return the entry */
  return Entry;
}

/*****************************************************************************/
/*                                   Code                                    */
/*****************************************************************************/

SymTable *GetSymTab(void)
/* Return the current symbol table */
{
  return SymTab;
}

SymTable *GetGlobalSymTab(void)
/* Return the global symbol table */
{
  return SymTab0;
}

SymTable *GetLabelSymTab(void)
/* Return the global symbol table */
{
  return LabelTab;
}

int SymIsLocal(SymEntry *Sym)
/* Return true if the symbol is defined in the highest lexical level */
{
  return (Sym->Owner == SymTab || Sym->Owner == TagTab);
}

void MakeZPSym(const char *Name)
/* Mark the given symbol as zero page symbol */
{
  /* Get the symbol table entry */
  SymEntry *Entry = FindSymInTable(SymTab, Name, HashStr(Name));

  /* Mark the symbol as zeropage */
  if (Entry) {
    Entry->Flags |= SC_ZEROPAGE;
  } else {
    Error("Undefined symbol: '%s'", Name);
  }
}

void PrintSymTable(const SymTable *Tab, FILE *F, const char *Header, ...)
/* Write the symbol table to the given file */
{
  unsigned Len;
  const SymEntry *Entry;

  /* Print the header */
  va_list ap;
  va_start(ap, Header);
  fputc('\n', F);
  Len = vfprintf(F, Header, ap);
  va_end(ap);
  fputc('\n', F);

  /* Underline the header */
  while (Len--) {
    fputc('=', F);
  }
  fputc('\n', F);

  /* Dump the table */
  Entry = Tab->SymHead;
  if (Entry == 0) {
    fprintf(F, "(empty)\n");
  } else {
    while (Entry) {
      DumpSymEntry(F, Entry);
      Entry = Entry->NextSym;
    }
  }
  fprintf(F, "\n\n\n");
}

void EmitExternals(void)
/* Write import/export statements for external symbols */
{
  SymEntry *Entry;

  Entry = SymTab->SymHead;
  while (Entry) {
    unsigned Flags = Entry->Flags;
    if (Flags & SC_EXTERN) {
      /* Only defined or referenced externs */
      if (SymIsRef(Entry) && !SymIsDef(Entry)) {
        /* An import */
        g_defimport(Entry->Name, Flags & SC_ZEROPAGE);
      } else if (SymIsDef(Entry)) {
        /* An export */
        g_defexport(Entry->Name, Flags & SC_ZEROPAGE);
      }
    }
    Entry = Entry->NextSym;
  }
}

void EmitDebugInfo(void)
/* Emit debug infos for the locals of the current scope */
{
  const char *Head;
  const SymEntry *Sym;

  /* Output info for locals if enabled */
  if (DebugInfo) {
    /* For cosmetic reasons in the output file, we will insert two tabs
    ** on global level and just one on local level.
    */
    if (LexicalLevel == LEX_LEVEL_GLOBAL) {
      Head = "\t.dbg\t\tsym";
    } else {
      Head = "\t.dbg\tsym";
    }
    Sym = SymTab->SymHead;
    while (Sym) {
      if ((Sym->Flags & (SC_CONST | SC_TYPE)) == 0) {
        if (Sym->Flags & SC_AUTO) {
          AddTextLine("%s, \"%s\", \"00\", auto, %d", Head, Sym->Name, Sym->V.Offs);
        } else if (Sym->Flags & SC_REGISTER) {
          AddTextLine("%s, \"%s\", \"00\", register, \"regbank\", %d", Head, Sym->Name, Sym->V.R.RegOffs);

        } else if (SymIsRef(Sym) && !SymIsDef(Sym)) {
          AddTextLine("%s, \"%s\", \"00\", %s, \"%s\"", Head, Sym->Name, (Sym->Flags & SC_EXTERN) ? "extern" : "static",
                      Sym->AsmName);
        }
      }
      Sym = Sym->NextSym;
    }
  }
}
